This invention is directed to a magnetic recording disk and a process of preparing the same wherein the thickness of the recording layer at the inner track zone or the area of the disk displaced toward the central hub of the disk is thinner than the thickness of the recording layer radially displaced outwardly from this inner track zone. During construction of the disk a positive charge is induced onto those areas which will correspond to the inner track zone of the recording layer by contact of these areas with an anodic metal which is more electro-positive than any metal component of the recording layer.
In the computer industry for the storage of large amounts of material in the computer industry disks containing magnetic recording layers are routinely used. Recent advances in the technology associated with the use of these disks has resulted in achieving higher and higher bit densities on smaller disks. Routinely, presently, five inch disks now are utilized where 14" disks were used in the past. The use of these smaller diameter disks are the direct result of increases in the bit density on the recording layers of the disks.
It is know that the use of thinner film thicknesses for the recording layer results in achievement of higher bit densities. This is especially true at higher frequencies wherein the thinner the film thickness of the recording media the higher the output of the bits recorded thereon.
The recording disks are spun under a transducer or recording head. Present technology allows the placement of the recording head at a flight height approaching zero with respect to the uppermost layer of the disk. Because the flight height of the recording head does approach contact with the surface of the recording disk recording disks prepared such as those in U.S. Pat. No. 4,224,381 for which I am a co-inventor, are used to prevent catastrophic loss of the recorded media on that disk when contact is made between the recording head and the upper surface of the disk.
The bits density recorded on the recording layer of a disk are located in tracks which extend outwardly from the center or hub area of the disk toward the outside periphery of the disk. Because the disk is round and because the center of rotation of the disk is at the center of the disk the velocity of the disk movement underneath the recording head is less at the inner tracks which have a smaller radius from the center of the disk than it is with respect to the outer tracks which are at a larger radius from the center of the disk. Additionaly, the track length at the inner tracks is much smaller than the track length at the outer tracks. Because the track length at the inner tracks is less than the track length at the outer tracks there is a higher bit packing density at the inner tracks with respect to the outer tracks. Because the bit density is higher at the inner tracks the output at the inner tracks is different from the output at the higher tracks.
In order to have a consistant interrelationship between the recording head and the recording disk it would be desirable to have a consistant output from both the inner and the outer recording tracks as well as all intermediate tracks between the same. In known recording disks it has heretoafore been impossible to achieve this consistant output because all heretoafore known magnetic recording disks have sought to achieve a consistant film thicknesses of all the layers constituting the disks including the recording layer.